Shift in foraging grounds and diet broadening during ontogeny in southern elephant seals from Kerguelen Islands
Shift in foraging grounds and diet broadening during ontogeny in southern elephant seals from Kerguelen Islands
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DOI：
10.1007/s00227-012-2149-5
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发表时间：
2013-04-01
期刊：
影响因子：
2.4
通讯作者：
Guinet, Christophe
中科院分区：
文献类型：
--
作者：
Chaigne, Adrien;Authier, Matthieu;Guinet, Christophe
高度二型的物种，如南象海豹（Mirounga leonina，以下简称SES），经常根据性别和/或年龄类别进行资源分配。从2004年到2011年，我们测量了404份血液样本（136名男性和268名女性，来自Kerguelen群岛，49 A度21'S，70 A度18 'E）的碳和氮稳定同位素（δ C-13和δ N-15）。假设碳同位素的分布（δ C-13值）反映了两个主要的觅食地（极地锋区和南极区），我们量化了每个区域内SES觅食的比例与大小的关系，这是它们年龄的代理。我们发现，从极地锋面到南极沃茨的男性SES年龄的明显转变，但没有关系，就女性而言。我们还观察到氮同位素（δ N-15）值的范围不断扩大，这表明男性和女性都随着年龄的增长而扩大了饮食谱。而男性增加其营养水平，女性平均保持不变，一些成年女性喂养在较低和较高的营养水平比少年。
Highly dimorphic species like southern elephant seals (Mirounga leonina, SES hereafter) frequently exhibit resource partitioning according to sex and/or age classes. We measured carbon and nitrogen stable isotopes (delta C-13 and delta N-15) of 404 blood samples (136 males and 268 females from Kerguelen Islands, 49A degrees 21'S, 70A degrees 18'E) from 2004 to 2011. Assuming that the distribution of carbon isotopes (delta C-13 value) reflects the two main foraging grounds (Polar Frontal and Antarctic Zones), we quantified the proportion of SES foraging within each zone in relation with size, a proxy for their age. We found a clear shift from Polar Frontal to Antarctic waters as male SES aged, but no relation as far as females is concerned. We also observed a widening range of nitrogen isotopic (delta N-15) values, suggesting that both males and females expanded their diet spectra with age. Whereas males increased their trophic level, females remained constant on average, with some adult females feeding both at lower and at higher trophic levels than juveniles.